In communication systems, signals are often transmitted over very long distances. Such long distances may cause signals to become degraded, for example, by attenuation and interference. Accordingly, some systems use signal converters to receive a degraded signal and restore its shape and amplitude.
Fiber optics-based communication systems in the past have used electrical signal converters that receive the light signal from the optical transmission medium, change that signal to an electric signal, restore the shape and amplitude, and change the signal back to light for transmission over another optical medium. Advances in fiber optics technology have allowed for the development of optical wavelength conversion, which performs the conversion without changing the signal to an electric signal. However, traditional optical wavelength converters have suffered from the effects of the pattern dependent effect and poor extinction ratios.